This mimics tlauion's OEM work in the sense that a user (or OEM) could
choose this option and it will reset an OpenPGP smart card and
automatically generate a random key on it. The idea is to allow an OEM
to set up a Librem Key and Heads on a machine before shipping with a
random key, so the user can test for tampering when they receive the
machine, and then the user can choose to reset all of the keys with
their chosen keys after that fact.
This change updates the very basic GPG smartcard feature in the GPG GUI
so that it can properly support generating a key from within Heads. It
offers the user the option to copy the generated GPG public key to a USB
thumb drive so it's not lost as well as the option to reflash the
current Heads BIOS with this new public key added to the keyring.
I've moved the common functions required to flash a new ROM with GPG
changes into a shared function at the top of the script.
It makes more logical sense for GPG functions to be split out into their
own menu instead of being part of the "Flash" menu. This creates a
gpg-gui.sh script and moves GPG options there while adding a few
additional features (like listing keys and initial smartcard key
generation support).
